Scripting in C# - Cannot Get New Objects to Create

Unity Engine
1

Hello all! I am new to Unity, but have been using C# for a little while now. I am having trouble instantiating new objects through code. To start let me explain what I am trying to do. I am trying to make a vehicle script in C# and at the point in which I need to make WheelColliders. I am storing everything in a simple data type (as a class for future functionality, but is basically a struct for now):

class WheelData
{
	//var X = 0;
	//var Y = -0.00000000373;
	//var Z = 0.0025;
	public double rotation = 0.0;
	public WheelCollider coll ;
	public Transform graphic ;
	public double maxSteerAngle = 0.0;
	public float lastSkidMark = -1;
	public bool powered = false;
	public bool handbraked = false;
	public Quaternion originalRotation ;
};

I have comment placed where I am getting a null reference upon runtime. Here is my current interpretation of how to do what I want:

// Use this for initialization
void Start () 
{
	// setup wheels
	// allocate memory
	wheels = new WheelData[4];
	// initialize objects
	for (int i = 0; i < 4; i++)
		wheels[i] = new WheelData();
		
	wheels[0].graphic = transform.Find("WheelFL");
	wheels[1].graphic = transform.Find("WheelFR");
	wheels[2].graphic = transform.Find("WheelBL");
	wheels[3].graphic = transform.Find("WheelBR");
		
	wheels[0].maxSteerAngle = 30.0;
	wheels[1].maxSteerAngle = 30.0;
	wheels[2].powered = true;
	wheels[2].handbraked = true;
	wheels[3].powered = true;
	wheels[3].handbraked = true;
		
	foreach(WheelData w in wheels)
	{
		if(w.graphic == null)
			Debug.Log("You need to assign all four wheels for the car script!");
		if(!w.graphic.transform.IsChildOf(transform))
			Debug.Log("Wheels need to be children of the Object with the car script!");
			
		w.originalRotation = w.graphic.localRotation;
			
		// create colliders
		WheelCollider colliderObject = new WheelCollider();

		// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
		// ~~~~~Here I am getting  Null Reference~~~~~
		// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

		colliderObject.transform.parent = transform;

		// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
		// ~~~~~Here I am getting  Null Reference~~~~~
		// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

		colliderObject.transform.position = w.graphic.position;
		w.coll = colliderObject;
		w.coll.suspensionDistance = suspensionDistance;
		JointSpring js = new JointSpring();
			js.spring = springs;
			js.damper = dampers;
			js.targetPosition = targetPosition;
		w.coll.suspensionSpring = js;
		w.coll.center = w.graphic.localPosition;
			
		// no grip, as we simulate handling ourselves
		WheelFrictionCurve noStiffnessFrictionCurve = new WheelFrictionCurve();
		noStiffnessFrictionCurve.stiffness = 0;
		w.coll.forwardFriction = noStiffnessFrictionCurve;
		w.coll.sidewaysFriction = noStiffnessFrictionCurve;
		w.coll.radius = wheelRadius;
	}

	// get wheel height (height forces are applied on)
	wheelY = wheels[0].graphic.localPosition.y;
}

The line : colliderObject.transform.parent = transform; seems be the problem, but I am not understanding what I have done wrong.

Any help would be appreciated.

2

object.transform is a property, not a variable reference.
You should normally get an error on that line

What you need to do is store out the transform into a Transform instance, change the content you want and potentially store it back into the object.

The other problem I see is that you use new in conjunction with Unity components.
Thats a big fat no go.
Never use new to initiate them

Instead attach the collider to the game object in question through AddComponent(typeof(WheelCollider))

3

Thank you for the advice!

Implementing changes now.

4 
// create colliders
GameObject colliderObject = new GameObject("WheelCollider_" + w.graphic.name);
colliderObject.transform.parent = transform;
colliderObject.transform.position = w.graphic.position;
colliderObject.AddComponent(typeof(WheelCollider));
w.coll = (WheelCollider)colliderObject.GetComponent("WheelCollider");

This is the fix I implemented in order to create the WheelCollider objects as actual GameObjects so that they are physically seperate from the body/wheels and thusly I can rotate the wheels and move various other things without affecting the WheelCollider transforms.